Onan 5500 Generator in Holiday Rambler 1998 Endeavor

Yesterday I spoke to friend at RV Dealership and he told me to hold stop button in for 15 seconds to prime carb. I did that and generator started and ran for about 3-4 minutes. After that it would not start. Today we disconnected gas line from main tank to fuel pump and hooked hose up to fuel pump and dropped hose in gas can. Generator would not start. We come to conclusion that new carb. is not working and are going to clean old one and put it back on and see if Generator starts.